86 



Descriptive Zoology. 



CHARACTERISTICS OF ARTHROPODS. 



1. Arthropods have an external skeleton, or exoskeleton. 



2. This skeleton consists of a series of rings, movable 

 upon one another, i.e. the skeleton is segmented. 



3. Some of these rings, or segments, bear appendages 

 that are segmented. 



CLASSIFICATION OF ARTHROPODA. 



